Electric regulator responsive to phase difference of two currents



June 9, 1953 D. J. slKoRRA ELECTRIC REGULATOR RESPONSIVE T0 PHASE DIFFERENCE OF TWO CURRENTS Filed Jan. 20, 1951 CURRENT 2 Patented June 9, 1953 ELECTRIC REGULATOR RESPONSIVE TO `PHASE DIFFERENCE OF TWO CURRENTS Daniel J. Sikorra, Milwaukee, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application January 20, 1951, Serial No. 207,011

9 Claims.

tions in the quantity from a desired value pro-v' duce ya rotational torque in the motor to move the regulator and return the quantity to the desired value.

Such systems have the disadvantage that the impedance of the motor field circuit varies with variations in the frequency of the applied voltage, so that the operation of the regulator is affected by frequency variations. An additional disadvantage of such regulators is that in case of failure of the alternating current supply to the motor coils, the mechanical reference moves the regulator to an extreme position, causing unsafe operation of the regulator. A further disadvantage of such regulators is that heating of the motor eld coils varies the resistance of the field coils, thereby altering the operation of the regulator unless some type of compensation is provided.

These disadvantages may be overcome by utilizing a regulator embodying an alternating current torque motor which is insensitive to variations in the frequency of the applied voltage and which is operative to regulate either alternating or unidirectional quantities.

It is therefore an object of this invention to provide an electromechanical regulator which requires no mechanical reference for its operation.

It is a further object of the present invention to provide an improved electric regulator which is unaffected by variations of the frequency of the alternating currents flowing in the circuits thereof.

It is an additional object of the present invention to provide an improved electric regulator which is operative Ato regulate either alternating or unidirectional quantities.

It is a further object of the present invention to provide an improved electric regulator which is insensitive to temperature variations.

It is an additional object of this invention to provide an electric regulator utilizing the same means for amplifying a damping signal and for sensing deviations in the regulated quantity.

Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 diagrammatically illustrates the preferred embodiment of the invention;

Figs. 2 and 3 are curves illustrating the operation of component parts of the embodiment shown in Fig. l, and

Fig. 4 diagrammatically illustrates an alternate embodiment of the present invention.

Referring to Fig. 1, one embodiment of the invention is shown applied to the regulation of an operating characteristic of an alternating current generator 6 supplying a load circuit represented by conductors l. Generator 6 is provided with an armature 6a connected to conductors I and a field Winding 6b connected to a suitable controllable source of direct current, such as the armature 8a of an exciter generator 8. Exciter 8 is provided with a eld Winding 8b, the energization of which is controlled by the regulator of this invention.

Field Winding 8b is preferably connected across the armature 8a in series with an adjustable resistor 9. Resistor 9 has associated therewith a rocking contact sector II for varying the portion of resistor 9 which is connected in series with Winding 8b. Sector II is actuated through a shaft I2 by the rotor I3a of a torque induction motor I3. M'otor I3 is provided With a pair of mechanically displaced duplicate iield coils I 3b, I3c to control the torque of the motor. Coil |327 is serially connected With the Winding I5a of a linear inductive reactor I5 having a magnetic core |52) to form a first circuit, and coil I3c is serially connected With the reactance winding IIa of a saturable reactor I'I to form a second circuit. Reactor II is also provided with a pair of saturable cores I'Ib and a control or saturating Winding I lc. Cores I5b, I'Ib are each provided With an air gap of any suitable known form, which may be defined by shims 2l of nonmagnetic material inserted in the cores.

The rst and second circuits described above have substantial resistance in addition to reactance and are energized in parallel With each other from a suitable alternating current source,

such as the secondary Winding 22a of a trans-V former 22 having its primary Winding 22b con-A nected to conductors 'I. Owing to the inductance of coils I3b, I3c, Winding I 5a and winding I'Ia, the currents through these elements will lag the applied voltage by an appreciable angle. To improve the power factor of the circuits, equal 3 capacitors 32, 33 may be connected as shown in Fig. l.

Control winding IIc has impressed thereon a unidirectional voltage proportional to the magnitude of the operating characteristic being regulated. lf it is desired to maintain the voltage of armature ta substantially constant at a predetermined value, winding Ilc may be supplied with a voltage proportional to the voltage of armature 6a through a full wave rectier 25 having its alternating current terminals connected across secondary winding 22a and having its direct current terminals connected across winding I'Ic in series with an adjustable resistor 2B. The saturation of cores IIb and the reactance of winding Ila therefore vary in response to variations in the magnitude of the voltage of armature 6a from the predetermined value.

The volt-ampere characteristic of reactor I may be represented by the straight line of Fig. 2, while the volt-ampere characteristics of reactor I'I' for different fixed values of direct current traversing winding I'Ic may be represented by the family of curves of Fig. 3. Fig. 3 shows that by suitable adjustment of the current through winding I'ic to produce a volt-ampere characteristic for reactor Il as shown by curve 3| of Fig. 3, the volt-ampere characteristics of reactors I5 and I1 will be substantially identical over a wide range of voltage and current.

A vdamping transformer 3d having a primary winding 34d connected across eld winding 6b and a secondary winding Elib connected across winding I'Ic may be provided to impress on winding I'Ic a stabilizing voltage proportional to the rate of change of the voltage of winding 8b.

In operation of the system, assuming that machines 3 and S are operating, the voltage of armature 5a has a magnitude determined by the energization of field winding 5b, which energication is in turn dependent upon the energization of i'leld winding 8b controlled by the amount of resistor d connected in series therewith. Assuming that the voltage of armature 6a has the desired value, secondary winding 22a impresses on the rst and second circuits and on rectifier 25 a voltage proportional to the voltage of armature 5a to produce a predetermined reactance in winding |10.. Resistor 25 is preferably so adjusted that when thevoltage of armature 6a has the desired value, reactor II has the voltampere characteristic shown by curve 3|, substantially identical to the volt-ampere characteri'stic of reactor I5. Under these conditions, assuming field coils |319, I3c to have equal impedances, equal currents flow through the first and .second field coil circuits and the currents are alsoin phase with each other. Since the torque of motor I3 is proportional to the product of the currents through coils I3b, I3c multiplied by the sine of the phase displacement angle between the currents in coils I3b, |30, the torque of motor I3 under these conditions is zero. Motor I3 therefore maintains sector II in its present position to maintain the voltage of armature 6a at the desired value. If the voltage of armature @d increases above the desired value, the voltage impressed on rectier 25 by secondary winding 22a. increases to increase the saturation of cores I'Ib and thereby reduce the reactance of winding I'Id. As the circuit of coil has substantial eective resistance,.a reduction in the reactance of winding I'Ia causes the current through coil |30 and winding I'Ia to become less lagging than before,

thereby producing a phase difference between the currents in the first and second circuits to produce a rotational torque in motor I3. Motor I3 thereupon rotates to move sector II through shaft I2 to increase the amount of resistor 9 connected in series with field winding 8b. This action reduces the voltageof Varma-ture Sa to thereby reduce the energization of field winding b to return the voltage of armature da to the desired value. When the voltage of armature 6a has. returned to the desired value, the second circuit again has the volt-ampere characteristic of curve 3| to produce Zero torque in motor I3, causing sector II to remain in its new position to maintain the voltage of armature 8a at the desired value. During the above described operation, transformer 35| impresses on winding IIc a stabilizing voltage proportional to the rate of change of the voltage across field winding 8b., which `stabilizing voltage is considerably amplified by reactor I toprevent hunting of the regulator. Thus, reactor I'iacts to both sense deviations in the regulated quantity and to amplify a damping signal to the regulator.

If thevoltage of armature 5a decreases below the desired value, the action of the regulator to return the voltage to the .desired value is the reverse of that described above.

If the speed of machine 5 changes, the frequency of the voltage of armature iid and conductors 'I changes to vary the reactances of windings Ia, Ila. However, lsince windings I5a, Ilal have substantially identical volt-ampere characteristics when the voltage of armature ila is normal, changes in the frequency of the voltage of armature 6a produce equal changes in the reactances of windings Ia, Ila, so that the eiTect of the frequency changes on the regulator is negligible. The volt-ampere characteristics of reactors I5 and I'I therefore undergo equal predetermined changes in response to variations in the frequency of the applied voltage to provide a frequency insensitive regulator. After the regulator has been operating for some time, the heating of field coils |35, I3c produces changes in the. resistances of the ield coils to vary the currents through the rst and second circuits. However, these resistance changes are without effect on the regulator, since the rst and second circuits are electrically symmetrical, causing the two circuit currents to remain in phase with each other when the regulated quantity has the desired value.

Fig. l illustrates an alternate embodiment of f the invention applied to the regulation of a undirectional quantity. In the embodiment of Fig. 4, the regulator is utilized to control the'voltage of the armature la of a direct current generator 4I supplying a load circuit d2. Generator lII is provided with a eld winding ill? supplied from armature 8a of exciter 3, and resistor 9 is connected in circuit with eld winding 8b as in Fig. l. Reactor I5 in the rst circuit of Fig. l is replaced in Fig. 4 by a reactor fifi, provided with a reactance winding diie. Reactor it is also provided with suitable bias means to bias cores Mb to a predetermined fixed reference level, such as permanent magnets d5 associated. with cores Mib.

Coil I3b is connected in series with reactance winding ifi-a and a capacitor 32 to form a iirst circuit, and coil ISC is connected in series with capacitor 33 and winding Vd to form a second circuit. These circuits are energized in parallel with each other yfrom a suitable source of alternating current, represented by an alternator 52. Control winding l'lc is provided with a measure of the regulated quantity by being connected across circuit 42 in circuit with a xed resistor 50 and an adjustable resistor 53 to vary the saturation of cores Hb in response to variations in the voltage of armature v41a and circuit 42.

Damping transformer 34 has its primary winding 34a connected across iield winding v8b and has its secondary winding 34D connected across Winding I 1c to impress on Winding Hc a stabilizing voltage proportional to the rate of change of the voltage of winding 8b.

Permanent magnets 45 in cores 44h produce a fixed reference magnetic bias source for cores 44h. Magnets 45 also act as small air gaps in cores 44h, so that reactor 44 has a volt-ampere characteristic substantially identical to curve 3| for one strength of magnets 45. Resistor 53 is so adjusted that when the voltage of armature 41a has the desired value reactor i1 also has vthe volt-ampere characteristic represented by curve 3|, so that windings l'la, 44a have equal reactances when the voltage of armature' 4I'a has the desired value. Under these conditions the currents through coils I 3b, |`3c are equal and in phase so that the torque of motor VI3 is zero Yto maintain sector H in its existing position to keep the voltage of armature 41a at the desired value.

If the voltage of armature 4Ia increases above the desired value, the voltage impressed on winding I'Ic increases to decrease the reactance of winding Ha. The current through winding Ilcr and coil I3c thereupon becomes less lagging than the current through winding .44a and coil |3b, l

producing a torque in motor I3 to rotate sector Il. Sector ll increases the amount of resistor 9 connected in series with iield winding 8b to reduce the voltage of armature 8a and return 'the' voltage of armature 4lo to the desired value. During the above* described operation, the stabilizing voltage impressed on Winding'Hc by winding 3413 is amplied by reactor I1 to prevent hunting of the system.

1f the voltage of armature 41a decreases below the desired. value, the action of the regulator to return the voltage to the desired value is th reverse of that described above.

It will be noted that the strength of magnets 45 and the adjustment of resistor 53 may be varied to vary the volt-ampere characteristics of reactors Il, 44 so that the reactors operate von any of the volt-ampere characteristics of Fig. 3. If the Volt-ampere characteristics of reactors I1, 44 are adjusted so that they are substantially identical, the regulator will be insensitive Atovariations in frequency or magnitude of the voltage' of alternator 52, since such variations will produce equal effects on windings Ha, 44a.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that Various changes and modications may be' made therein without departing from the spirit of the invention as set forth in the appended claims.

In particular, the volt-ampere characteristics of the rst and second circuits need not Ybeloo-v incident as long as the two characteristics have the same shape and the rirstand secondcircuits operate at the same power factor when the regulated quantity has the desired value. That is, the magnitudes of the currents through the first and second circuitsV may have any relation to each other'a'sy long as the currents inthe two circuits are in phase with each other when the regulated quantity has thev desired value. Also, it will be apparent that the embodiments of Figs. 1 and 4 are equally eiective to regulate either alternating or unidirectional quantities.

It is claimed and desired to secure by Letters Patent:

1. In a system for maintainingv a quantity substantially constant at a predetermined value, the combination of regulating means including a motor for controlling the magnitude of saidquantity, said motor comprising a first eld coil and a` second eld coil, a linear reactor connected in series with said first field coil to form a rst circuit, a saturable reactor having a reactance Winding and a control winding, means connecting said reactance winding in series with said second field coil to form a second circuit, a source of alternating current for energizing said rst and second circuits, the relative phase of the currents in said rst and second circuits determining the direction of rotation of said motor, and means connected to said control winding for impressing on said control Winding a unidirectional voltage proportional to the magnitude of said quantity to cause the saturation of said saturable reactor to vary in response to variations in the magnitude of said quantity, whereby said motor rotates in the one or the other direction in response to variations in said quantity from said predetermined value to maintain said quantity substantially constantat said predetermined value.

2. In a system for maintaining a quantity constant, the combination of regulating means including a motor for controlling the magnitude of said quantity, said motor comprising a iirst field coil and a second field coil, a linear reactor, a rst capacitor, means connecting said first field coil, said rst' capacitor and said reactor in series to form a rst circuit, a saturable reactor having a reactance winding and a control winding, a second capacitor, means connecting said second eld coil, 4said'second capacitor and said reactance Winding in series to form a second circuit,ra source of alternatingv current for energizing said rst and second circuits, the relative phase of the currents in said iirst and second circuits determining the direction of rotation of said motor, and means for impressing on said control Winding a unidirectional voltage proportional to the magnitudeof said quantity to cause said motor torotate in a direction to maintain said quantity substantially constant.

3. In a system for maintaining a quantity substantially constant at a predetermined value, the combination of regulating means including a motor for controlling the magnitude of said quantity, said motorV comprising a first iield coil and a second field coil, the relative phaseV of the currents in said rst and second eld vcoils determining the direction of rotation of said motor, a linear reactor having predetermined voltampere characteristicspfor varying frequencies or applied voltage, means connecting said linear reactor in series with said rst held coil'to form a rst circuit, a saturable reactor having a reactance Winding and a control Winding, means connecting said reactance winding in series with said second field coil to forma second-circuit, a source of alternating current for energizing said first and second circuits, means for impressing on said control winding a unidirectional voltage proportional to the magnitude of said quantity to cause the saturation of said saturable reactor to vary in response to variations in the magnitude of said Yquantity from-saidA predetermined' value,v and-'means for adjusting the magnitude of said unidirectional voltage to cause said saturable reactor to havesaid predetermined volt-ampere characteristics when said quantity has said predetermined value.

. li. In a system for maintaining a quantity substantially constant at a predetermined value, the combination of regulating means including a motor for controlling the magnitude of said quantity, said motor comprising a rst field coil and a ysecond eld coil, the relative phase of the currents in said first and second field coils determining the direction of rotationy of said motor, a rst saturable reactor having a first reactance Winding connected in circuit with said first eld coil to form a first circuit, bias means for said first reactor, saidfirst reactor having predetermined volt-ampere characteristics for varying frequencies of applied voltage, a second saturable reactor having a second reactance winding and a control Winding, means connecting said second'reactance Winding in series with said second eld coil to form a second circuit, a source of lalternating current for energizing said rst and second circuits, means for impressing on said control Winding a unidirectional voltage proportional to the magnitude of said quantity to vary the saturation of said second reactor in respense to variations in the magnitudeof said quantity from said predetermined value, and means for adjusting the value of said unidirectional voltageto cause said second reactance winding to have saidv predetermined volt-ampere characteristics for varying frequencies of applied voltage when said quantity has said predetermined value.

5. In a system for maintaining a quantity substantially constant at a-predetermined value, the combination of regulating ymeans including a motor for controlling the magnitude of said quantity, saidmotor comprising a first eld coil and a'second neld coil, the relative phase of the currents in Asaid rst and second :lield coils determining the direction of rotation of said motor, a first saturable reactor-having a first reactance Winding connected in circuit with said first field coil to form a rst circuit, bias means for said iirst reactor, said first reactor having a predetermined linear volt-ampere characteristic, a second saturable reactor having a second reactance Winding and a control winding, means connecting said second reactance Winding in series with said second eld coil to form a second circuit, a source of alternating current for energizing said first and second circuits, means for impressing on-said control Winding a unidirectional voltage proportional to the magnitude of said quantity to vary the saturation of said second reactor in response to variations in the magnitude of said quantity `from said predetermined value, and means -for adjusting the value of .said unidirectional voltage to cause said second reactor to have said predetermined volt-ampere characteristic when said quantity has said predetermined value.

6. In a system for maintaining a quantity substantially constant at a predetermined value, the combination of regulating means including a motor for controlling the magnitude of said quantity, said motor comprising a first field coil and a second field coil, a first capacitor, a firstsaturable reactor having a rst reactance winding connected in serieswith said first coil and said first capacitor to form a first circuit, bias means for saidnrst'reactor to lcause said rst reactor'to have a predetermined linear volt-ampere characteristic, a second saturable reactor having a second reactance winding and a control Winding, a second capacitor, means connecting said second reactance Winding, said second capacitoi` and said second field/coil in series to form a second circuit, a sourceof alternating current for energizing said rst and said second circuits, the relative phase'of the currents in said field coils determining the direction of rotation of said motor, means for impressing on said control winding a unidirectional voltage proportional to the magnitude of said quantity to cause the saturation of said second reactor to vary in response to variations in said quantity, and means for adjusting the value of said unidirectional voltage to cause said 'second'reactor to have said predetermined volt-ampere characteristic when said quantity has said predetermined value.

7. In a system for maintaining a quantity substantially constant at a predetermined value, the combination of a direct current circuit for controlling the magnitude of said quantity, a motor for controlling the magnitude of the-voltage of said direct current circuit, said motor comprising a rst field coil and a second iield coil, a reactor having a predetermined linear voltampere characteristic, means connecting said reactor in series ywith said iirst field coil to form a first circuit, a saturable reactor having a reactance winding and a. control Winding, means connecting said Vreactance winding in series with said second field coil to 'form a second circuit, a source of alternating current for energizing said rst and second circuits, the relative phase of the currents iny said first and second circuits determining the direction of rotation of said motor, means for impressing on said control winding a unidirectional voltage proportional to the magnitudeof saidA quantity to vary the saturation of said saturable reactor in response to variations in said quantity from said predetermined value, means for adjusting the magnitude of said unidirectional voltage to cause said saturable reactor 'to have said predetermined voltampere characteristic when said quantity has said desired value, and a damping transformer havingy aprimary winding connected to said direct current circuit and a secondary winding connected to said control Winding to impress thereon a stabilizing voltage proportional to the rate of change of the voltage of said direct current circuit.

`8. Ina-system Vformaintaining a quantity substantially fconstant at a predetermined value, the, combination of a -direct current circuit for controlling the magnitude of said quantity, a motor ,for controlling Athe vmagnitude of the voltage of said direct current circuit, said motor comprising a first iield coil and a second iield coil, a -reactor having a predetermined voltampere characteristic, means connecting said reactor in series With said first eld coil to form a first circuit, a saturable reactor having a reactance Winding and a control Winding, means connecting said reactance Winding in series with said second field coil to form a second circuit, av source of alternating current for energizing said rst and second circuits, the relative phase of the currents in sai-d first and second circuits determining the direction of rotation of said motor, means for impressing on said control Windinga unidirectional voltage proportional to the magnitude ofk said quantity` to vary the saturation of said saturable reactor in response to variations in said quantity from said predetermined value, means for adjusting the magnitude of said unidirectional voltage to cause said saturable reactor to have said predetermined voltampere characteristic when said quantity has said desired value, and damping means connected to said direct current circuit and to said control Winding for impressing on said control winding a stabilizing Voltage proportional to the rate of change of the voltage of said direct current circuit.

9. In a system for maintaining a quantity substantially constant at a predetermined value, the combination of regulating means including a motor for controlling the magnitude of said quantity, said motor comprising a iirst eld coil and a second iield coil, a reactor having a voltampere characteristic which undergoes predetermined changes in response to variations in the frequency of the voltage applied to said reactor, a rst capacitor, means connecting said reactor in series With said iirst capacitor and said iirst field coil to form a first circuit, a saturable reactor having a reactance Winding and a control winding, a second capacitor, means connecting said reactance winding in series With said second capacitor and said second field coil to form a second circuit, a source of alternating current for energizing said iirst and second circuits, the relative phase of the currents in said iirst and second circuits determining the direction of rotation of said motor, means for impressing on said control winding a unidirectional voltage proportional to the magnitude of said quantity to vary the saturation of said saturable reactor in response to variations in said quantity, and means for adjusting the magnitude of said unidirectional voltage to cause the volt-ampere characteristic of said saturable reactor to undergo said predetermined changes in response to said Variations in the frequency of the applied voltage when said quantity has said predetermined value.

DANIEL J. SIKO-RRA.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,841,082 Biggs Jan. l2, 1932 2,399,872 Krussmann May 7, 1946 2,414,569 Tubbs Jan. 21, 1947 2,473,791 Doremus June 2l, 1949 2,477,728 Fitzgerald Aug. 2, 1949 2,504,909 Tubbs Apr. 18, 1950 

